TBI Cam/Stall/Tuning Questions

Discussion in 'Engine Performance + Maintenance' started by Andrew Warfield, Jul 10, 2019.

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  1. Andrew Warfield

    Andrew Warfield Newbie

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    Hey guys,

    I have a 95’ Tahoe. Engine and trans. were replaced back in 2016 with a GM crate long block (12568758) and an OEM 4L60E.

    I have already installed a new TBI Unit (Fully Rebuilt with New Injectors/TPS/IAC, Bored 46mm/650cfm, Adjustable Fuel Pressure Regulator (Injector Pod must be removed to adjust) with 18psi spring, Pressure is set at 18psi. max is 20psi., 46mm matching Square-Bore Carb Style Intake Adapter, Air Flow Enhancer Ring, K&N Filter with Top). And a full exhaust system (3in. tubing, RPC Mid-Length Ceramic Coated Headers, Flowmaster Y-Pipe, Flowmaster 200 High-Flow Cat, Borla ProXS Muffler, New AC Delco 3-wire O2 Sensor).

    I am going to install a set of Trick Flow Aluminum Super 23, 175cc Intake /67cc Exhaust, 56cc Combustion Chamber with GM Composite Head Gasket: Part Number: NAL-10105117, Thickness: .028 (Compression ratio needs to be checked properly: Goal is a 10:1 ratio).

    Also, for the intake, Edelbrock EPS, Square-Bore Carburetor Style (I have the adapter for the TBI unit).

    I am also going to install new AC Delco higher flowing fuel pump, spark plugs, wires, coil etc.

    My main questions are concerning camshaft selection, torque converter stall speed selection and tuning.

    Camshaft: So the block is roller ready, my choices are either

    1. COMP Computer Controlled Hydraulic Roller Kit, Part Number: K08-304-8, Advertised Duration: 266Int./276Exh. – Actual Duration: 210Int./220Exh. Lobe Separation Angle: 114, Valve Lift: 0.500Int./0.510Exh., RPM: 1400-5400 WITH 1.5 ROLLER ROCKERS

    Or

    2. COMP Computer Controlled Hydraulic Roller Kit, Part Number: K08-300-8, Advertised Duration: 262Int./264Exh. – Actual Duration: 206Int./210Exh. Lobe Separation Angle: 112, Valve Lift: 0.450Int./0.480Exh., RPM: 1000-5000 WITH 1.5 or 1.6 ROLLER ROCKERS??


    Now considering the cylinder heads and bored out TBI, which cam would be better for a daily driving/widest power band? Keeping in mind I’m willing to do extensive tuning and install a higher stall converter.

    Torque Converter Stall Speed: Considering the camshaft specs and the rest of the engine specs would an FTI Torque Converter: 9.5in., Lock-Up, 2800-3000RPM be a good choice?

    Has stock Rear Gears: 3.73 (Posi-Trac) and the Tires are 265/75R16, 31.6 Diameter, BFGoodrich Advantage T/A


    TUNING: What advice can you guys provide? I was considering purchasing the Moates APU1 auto prom package/usb version. What would need to be done is the following: Datalogging, Chip Burn, Adjust Fuel Pressure, Tuned Fuel Maps, Set Timing, Set Transmission Shift Points, EGR Delete, Speedometer Calibration, Speed Limiter Delete. Anything else you can think of? Would the Moates APU1 auto prom package be the best bet on the market?

    Thanks in advance for any and all help :)
     
  2. PlayingWithTBI

    PlayingWithTBI Desert Old Guy

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    I'm guessing you have a 5.7L with a 7427 PCM? With what you're planning, save some money for a new trans too, your 4l60E won't hold up. I've already gone through 2 700r4s before I broke down and had a stage 2 built. You may want to go to a 4l80E (or beef up your 4l60E). I'm running the 46mm TB with 61lb/hr injectors and a 28lb spring set to 27-28lbs. If you go much over 18lbs with your spring it will get spring bound.

    I don't have any experience with the APU1, before I went to the EBL I used TunerPro RT v5 (still do for programming), an ALDL/USB cable, and Moates Burn2 with a 27SF512 flash chip in a ZIF socket on my 7747 ECM. Yours is a little different application but, something to think about...
     
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  3. PlayingWithTBI

    PlayingWithTBI Desert Old Guy

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    I was thinking more about your project;
    Those heads have 1.94/1.50" valves and max valve lift .520" with 1.250" springs. You should check spring pressure and max RPM before you decide on what cam to buy. Take a look at these TBI heads (angled plugs too) .480 max lift. Either way you can change springs for higher lift and revs). You'd need a TBI intake for these...
    https://www.summitracing.com/parts/sum-162108/overview/make/chevrolet

    You confirmed the block has the bosses and was drilled and tapped for the spyder?

    Cam choice - You said you want to have a daily driver, the 1st cam with 114* separation will give you a pretty good lope at idle and, with a 2800 - 3000 TC you won't like driving in traffic or MPGs.

    My 88 has a Lunati Voodoo flat tappet cam 112* 207/213 @ 0.050 and .466/.484 lift w/1.6 roller rockers(here in AZ I still need to pass emissions) smooth idle and keeps up with traffic. I have a 2300 - 2500 stall TC. My trans is shifting ~5000RPM @ WOT keeping it within its power band.

    It's all personal opinion, I'm sure other folks here have their opinions too, and would love to see them. HTH - enjoy!
     
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  4. L31MaxExpress

    L31MaxExpress I'm Awesome

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    I had a flat tappet 218/218 @ .050 on a 110 lsa and 1.6 rockers in a 305 Vortec in my 99 Tahoe. Stock converter in it when I built it. It idled dead smooth at 750 rpm in drive. Fuel mileage was still very good.

    The 350 in my Express van has a 215/224 @ .050 roller with 1.7 rockers. Idle is also very smooth at 750 rpm. Fuel mileage is still good with 5.13 gears and a 2,800 stall.

    You have to get up into the mid 220s @ .050 before low-end torque starts to really become a noticeable loss and rough idle becomes an issue. I would consider anything 218 @ .050 or under at .050 tolerable with a stock converter. A 2,800-3,000 converter will wake up even a stock cammed engine. While idle vacuum is better and so is mileage a wider LSA will cost you cylinder pressure and lower rpm torque.

    With proper tuning a TBI ECM will idle at 8 in/hg in drive. I had a 232/240 @ .050 roller in my MPFI 383 running on a TBI PCM in my old G20 van years ago. S10 converter that stalled 2,800 rpm and 3.07 gears With the a/c on in Drive it made 8 in/hg of vacuum at 850 rpm. No idle or driveability issues.

    I personally prefer a high stall in traffic. The car/truck will idle in gear without trying to creep forward all the time without you standing on the brakes. Even a 3,000 rpm converter will typically move the vehicle under 1,000 rpm. I typically setup my engines and transmissions to make power up to the 5,500-6,000 rpm range.

    My daily driver is a 3.5L V6 with intake/exhaust and tune making about 340 hp. From the factory has a 3.91 rear gear, a factory 3,000 rpm converter and shifts WOT at 7,500 rpm. Cruising 75 mph @ 3,200 rpm it still gets 25 mpg.
     
    Last edited: Jul 10, 2019
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  5. Andrew Warfield

    Andrew Warfield Newbie

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    Thanks for your input. I see the Summit heads you mentioned do have larger intake and exhaust valves, however, the combustion chamber is also larger. I would like to stick with the smaller 56cc combustion chambers of the Trick Flow heads for the increased compression ratio. IYO wound not the higher compression ratio be more valuable in comparison to the larger valves?

    As for the cam, I'm still not sure of the choice between the 1st with 1.5 rockers or the 2nd with 1.6 rockers. My first guess would be the 1st choice with 1.5 rockers. But.... Which one??

    I will be using the Edelbrock EPS intake. I already have the matching adapter to go with my bored TBI unit. From SPR Performance, excellent quality and service, highly recommended with SPR!
     
    Last edited: Jul 12, 2019
  6. PlayingWithTBI

    PlayingWithTBI Desert Old Guy

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    Yeah, I got my stuff from him too.
     
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  7. L31MaxExpress

    L31MaxExpress I'm Awesome

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    I would ditch the self aligning rockers if you are running a good set of aftermarket heads and use guide plates. I run 1.7 rockers myself and 0.578" lift. With a good flowing head it helps to run alot of lift relative to the duration. Good valve springs are a must have though also be sure to check the PTV clearance.
     
  8. L31MaxExpress

    L31MaxExpress I'm Awesome

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    I am thinking something like this cam with a 1.7 rocker ratio. Lift would be 0.554". On a degree wheel the 0.050" duration would jump up to about 218/[email protected] .050 with 1.7 rockers with a relatively unchanged seat to seat duration. Should pull about 16 in/hg vacuum at 750 rpm and about 12-13 in gear.

    https://www.summitracing.com/parts/lun-20080679/make/chevrolet

    I would also take the opportunity to swap it to hydroboost at the same time. Get a diesel brake pedal and upgrade to the hydroboost booster and a 1-ton master cylinder. Gave my Express van a much needed inprovement in the braking department to match the massive power upgrade.
     
    Last edited: Jul 12, 2019
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  9. Andrew Warfield

    Andrew Warfield Newbie

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    Edited my post to say the summit heads have larger not smaller combustion chambers. My bad.
     
  10. PlayingWithTBI

    PlayingWithTBI Desert Old Guy

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    Don't forget to use hardened (Chromoly for example) push rods when running guide plates.
     

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